-LRB- CNN -RRB- -- Fifty-two years ago , the survivors of the Springhill Mine Disaster in Nova Scotia revealed a few things to the world about the brutality of survival in the depths .

Without food or water , cut off in every way from life on the surface , in a world lighted only by the head-lamps on their helmets until the batteries died and left them in profound darkness , the men struggled to escape and then prepared to die .

Psychologists , academics and journalists swamped the 18 men upon their miraculous rescue to hear their tales , take down their personal histories , and administer IQ and personality tests . These intensive examinations , repeated at yearly intervals , allowed experts to sketch a few conclusions about the psychology of group survival when hope , like light , is gone .

The rescue of the Chilean miners -- which ended this week in jubilation as every one of them ascended , healthy and sound , to the surface -- represents a triumph of space-age ingenuity and technology . It would have been unthinkable half a century ago .

Here is what happened then .

At 8:06 p.m. October 23 , 1958 , in Springhill , Nova Scotia , one of the deepest coal mines on Earth collapsed , with 174 men underground . Eighty-one men struggled to the surface , battered but alive and speaking of horrors below . Ninety-three were missing .

Fallen rock blocked access to the depths ; the mine had sealed up as if it had never existed . The world was watching : The Springhill Mine Disaster was the world 's first live-television-broadcast news event . Hundreds of people -- families , reporters , cameramen , officials and onlookers -- mobbed the mouth of the mine .

In Springhill , each rescuer crawled on his belly into the collapsed mine with a hand-ax , chipped away at the rock , filled a bucket , passed it back to the man lying behind him , who passed it to the next man in line , and in that painstaking way , a single bucket of rocks reached the surface . Those workers encountered only the crushed bodies of their comrades . Families buried their loved ones ; those without recovered bodies planned memorial services .

But the mine had collapsed in such a way as to create two air pockets , two caves not much bigger than closed freight elevators . In one cave a mile below the surface , seven men awoke from the crash in rock prisons ; at a deeper elevation , 12 men found themselves walled in together . Neither group heard the other .

On Wednesday in Chile , the rescued mine foreman spoke of the worst moment underground : When the dust settled , the men were able to look around and see their predicament . The same was true in Springhill . Coming to consciousness after the double earthquake of the collapse , lighting their head lamps , the men in each cave were staggered by the extent of the destruction .

These men had known the underground walkways and tunnels as well as their own neighborhoods ; now , all was twisted beyond recognition . Immediately , they began to search for an exit : they pried into every cranny and felt their way along jagged walls . In each group , a natural leader emerged .

Each of the leaders -LRB- the researchers later concluded -RRB- was a man short on words and poorly educated , handy with equipment , with a good navigational sense but poor interpersonal skills , confident that he would find or chop a way out . Following his lead , the other miners jury-rigged tools from broken pieces , chipped at the walls , hungrily ate leftover dinners and drank from canteens .

Other men privately wondered whether the food and water ought to be preserved and rationed in case escape was more than a few hours away , but they said nothing . The energy and optimism of the dexterous leaders lasted for about three days and gave out along with the food , water and lamp batteries .

In Chile , love moves the sun and stars

On the third day , even the crumbs were gone , canteens were dry , and head lamps blinked off . This was the deepest darkness on Earth . The handyman leaders sat down and gave up .

In the darkness , with no projects and work to distract them , the men could no longer avoid sad thoughts . They missed their families terribly and feared that the mine owners would n't take care of their widows and children . One man was heartened because it was Monday morning , so his daughter must be in school . Then he realized that the mine disaster probably caused the schools to close , and he felt lonely again , not knowing where his daughter was .

Men longed to take back words spoken in anger . One realized he 'd taken a couple of little things from a friend 's shop with the intention of paying a few days later . Now , he 'd never be able to pay ; now , it was as if he 'd stolen from his friend .

One man quietly wondered whether the other fellows knew that he had been born out of wedlock ; he 'd spent his life protecting the secret that he was a `` bastard . '' Then thirst came on and blotted out almost everything else on their minds : It seemed to turn their tongues to wood and cracked their lips and scraped their throats raw . The men pooled their urine in a bucket and used bits of cloth to moisten their lips .

Now , in both groups , new leaders arose . These -LRB- the researchers later determined -RRB- were more educated , had higher IQs and better interpersonal skills . They offered no escape plans and were not equipment experts . In the gassy pitch-black pits , their quiet voices sounded fatherly and moderate -LRB- one was the father of 12 -RRB- . They were not panicking ; they still had hope .

Their peaceful voices -- they spoke a little bit about God , a little bit about their certainty that rescuers were looking for them -- calmed the other men . Just being in the company of these thoughtful and kind men comforted the rest .

Another remarkable thing happened underground , and it was that conventional social barriers fell . In one of the groups , the second leader , the sharer of hope , was Afro-Canadian . Aboveground , others worked beside him cheerfully enough -- this was not the American South -- but he 'd always felt himself held at bay .

His family never socialized with any of theirs ; their wives were not friends . He , almost alone among the miners , could n't be said to have a best buddy on the crew . But now , in the dark , when only his deep and calm voice stood among them , race was a non-issue . He was more than equal . They looked to him as a leader .

The rescue of the trapped miners after five days for the group of 12 and seven days for the group of six -LRB- a lone man was found alive elsewhere -RRB- was celebrated worldwide with breaking news reports , live footage and jubilation . A few miners accepted an invitation to appear on `` the Ed Sullivan Show '' in New York . All of them traveled with their families to Jekyll Island , Georgia , at the state of Georgia 's expense , to relax and recuperate .

How will Chilean miners fare psychologically ?

But there , the realities of life on the Earth 's surface returned with a vengeance . Georgia was segregated ; only one motel , solely for whites , existed on Jekyll Island . Though the miners flew together to Jacksonville , Florida , Georgia authorities transported them to Jekyll in a white-only bus and a black-only bus , the latter exclusively for the Afro-Canadian miner and his family .

His fellow miners protested , but the black miner , Maurice Ruddick , insisted that he and his family would have a fine vacation -LRB- though they were housed in a trailer far from the hotel -RRB- , and he urged everyone to relax and enjoy .

The white vacationers enjoyed fishing trips , restaurants and a football game , while the Afro-Canadian family was entertained privately in the homes of black residents .

Thus was the fellowship that existed underground -- between black and white , educated and uneducated , those of legitimate birth and those born `` out of wedlock '' -- gradually dissolved by the bright light of day .

The opinions expressed in this commentary are solely those of Melissa Fay Greene .

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Melissa Fay Greene writes about Canada mine collapse that captured world 's attention

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20 men were trapped in darkness with no high-tech gear to free them , unlike Chile miners

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Social structure formed ; soon , a black man took lead , in contrast with his aboveground status

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Greene : Miners rescued , racial division resurfaced too ; fellowship dissolved in daylight